Assessment of a grain oriented wound core transformer for solid state converter

Abstract

The increasing part of intermittent renewable energy requires significant modifications of the electric grid. The introduction of smart nodes, where the power transfer can be adjusted in real time in addition to the classical voltage change and the galvanic isolation, becomes an important asset for the grid balance. Transformers associated with power electronic converters can ensure this function; they are known generically as Solid-State Transformers (SST). Their high specific power also opens opportunities for railway application. SSTs can be operated at high frequencies (a few tens of kHz), with ferrite or nanocrystalline cores operating at low flux densities. The paper proposes a complementary approach that consists in using transformers built with grain oriented electrical steel (GOES) wound cores, operating at medium frequencies (few kHz) and high flux densities. The reported work focuses on experimental assessment aiming to show that this option is now open for designing SST cells, which can be associated to reach bigger units.